Conventionally, an electrophotographic image forming apparatus such as a copy machine and a printer includes a mechanism for collecting untransferred toner particles from a photosensitive member. Also, a full color image forming apparatus including an intermediate transfer member on which toner images are transferred from the photosensitive members and then onto a sheet includes a mechanism for collecting untransferred toner particles from the intermediate member.
The collecting mechanism may be incorporated in the image forming apparatus in various ways. For example, Document 1 (JP 61-153683 A) discloses an image forming apparatus in which a container for the collected toner particles is combined with another container for receiving a supply toner to reduce the size of and increase the operability of the apparatus. Document 2 (JP 11-153901 A) discloses another image forming apparatus in which a container is partitioned by a flexible member to define chambers for the supply toner and the collected toner, respectively. Document 3 (JP 2006-18050A) discloses another image forming apparatus in which toner particles collected from the photosensitive member and also the intermediate transfer member are transported into the black toner developing device where they are reused for the image formation. Document 4 (JP 2003-228214 A) discloses another image forming apparatus including a first collecting mechanism for collecting respective untransferred color toner particles into the corresponding developing devices and a second collecting mechanism for collecting all the untransferred color toner particles into the black color developing device.
As described above, each collecting mechanism of the conventional image forming apparatuses is designed to transport the untransferred toner particles into a single, specific container. This results in that the container becomes full of the collected toner particles within a short period of time in circumstances where a considerably amount of toner is consumed, which requires to exchange the containers so frequently.